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Hoelen (Poria)

practical aspects of administering the herb

 

Background: What’s in a name?

pic1Hoelen refers to a mushroom cultivated in China on the roots of Chinese red pine trees (e.g., Pinus massoniana and Pinus tabuliformis); it also grows wild on these pines and other conifers, as well as on several hardwoods (1).  Some may wonder why the name “hoelen” is often used to refer to it.  This common name comes from the original botanical name—Pachyma hoelen—given by the Dutch botanist Georg Eberhard Rumphius, in his book on Indonesian herbs published posthumously in 1741.  Pachyma is from the Greek for thick outer skin (pachy-derma); Hoelen is a Dutch surname (Rumphius probably honored a colleague with this naming).  Lewis David von Schweinitz, the founder of American mycology (study of fungi), designated hoelen as Sclerotium cocos in 1821, using a genus name devised 30 years earlier to indicate ball-like fungi, and cocos from coconut, describing its form and typical size (see photo of the coconut-like mushroom ball uncovered at the base of a pine tree).    In 1822, the Swedish mycologist Elias Magnus Fries named it Pachyma cocos in his book Systematic Mycology.  One hundred years later, in 1922, the American mycologist Frederick Adolph Wolf identified the mushroom as a polypore and renamed it Poria cocos.  His two volume book, The Fungi, became a major resource for the study of mushroom species.  However, his revised nomenclature for this mushroom is far from the end of the renaming.  The mushroom was designated Macrohyporia cocos in 1979, Macrohyporia extensa in 1983, and then in 1984 it was named Wolfiporia cocos, these genus names separate this mushroom from other Poria fungi (the last version honoring the mycologist Fredrick Wolf); the other species of Poria produce long filaments rather than masses.  In the same year (1984) it was further recast as Wolfiporia extensa, the currently preferred botanical name.  The species name extensa had been applied to this mushroom back in 1891 by an American mycologist, Charles Peck, and that name was brought forward (2).

The first English-language book of Chinese herbs, compiled at the end of the 19th Century (3), used the botanical name Pachyma cocos, which was the accepted designation at the time.   Most of the herb books that come to us from China as English translations are based on books and articles written during the highly active period 1950-1980; the botanical name given in these is Poria cocos, the accepted designation from 1922–1979, so the mushroom is often referred to as poria.   But the texts from Japan (and from Taiwan, which adopted much of the Japanese literature) relied on the original Dutch designation, since the Dutch greatly influenced Japanese medicine and science, starting in 1639 (4).  The name “hoelen” came to American practitioners of Chinese medicine via the Oriental Healing Arts Institute (OHAI), which brought Japanese and Taiwanese literature to the U.S. in the 1970s.    Normally, the OHAI naming system uses the genus name (in this case, it would be pachyma) unless there are other commonly used herbs of the same genus, in which case the species name might be chosen, but there may have been other reasons for selecting hoelen, such as prior use in Japanese literature.   Modern Chinese medicine texts, including those written by Western authors, usually relay what is found in the Chinese sources, Poria cocos, without updating to the current nomenclature.   Any suggestion that “hoelen” is wrong and “poria” is correct would not be based on full knowledge of the nomenclature accepted today; the common names come to us because they have been frequently used for easy reference.

As noted, hoelen is a polypore; that is, it belongs to the family Polyporaceae, so-named because the members have many tiny pores.  The mushrooms of this family also have the characteristic of not possessing the ordinary mushroom shape (stalk and cap).  Poria species are known as wood-decaying fungi producing, for example, “poria root rot.”  In fact, the common problem of “dry rot” is typically caused by a species of Poria, such as P. incrassata.  These mushrooms, and others that grow on trees, contain enzymes (cellulases) that degrade the structural component of wood, cellulose.   Wolfiporia extensa eventually damages the pine roots, but it is not as devastating as the fungi that are currently listed as being species of Poria.

In books of Chinese medicine, the description of the material part of this fungus to be used is the “sclerotium.”  Sclerotium (plural: sclerotia) is a term that (in modern usage) refers to a dense mass of branched hyphae, which is what makes up hoelen. 

One will sometimes also see reference to an American term for hoelen: tuckahoe (5).  This name was first used in early American literature as a generic reference to edible roots; later, however, it was also applied to describe the sclerotial bodies of fungal origin, and now it is used almost exclusively for that purpose, and especially to refer to hoelen.  In Florida, where tuckahoe was routinely collected (growing on several types of trees; it is also found to some extent in other East Coast states as far north as New York), the Native Americans would sometimes use them for food, and so it has also been called “Indian bread.”  The mushrooms have a low nutritional value, providing some carbohydrate, but virtually no protein.  They have also been used as food in China, ground into flour and mixed with rice, then formed into cakes.

pic2The Chinese name for the mushroom is fuling; the characters are just phonetics applied to the spoken name of the herb, an ancient term.  The name may be modified to indicate the locale from which the material was collected; for example, from hoelen from Anwei may be called Anling, and that from Yunnan may be called Yunling.   The outer skin of hoelen is called fulingpi (pi=skin), which is separated off and provided as a separate medicinal item, with the reputation of being a good diuretic.

These mushrooms are only found underground (like truffles).   Poria can grow quite large, with a white interior and a dark brown exterior that may develop a mottled appearance like tree bark.  Because of its source below the ground and international distribution of the material collected from China, another designation for the mushroom has been “China root.”  This term has been used for over a hundred years, mainly for this mushroom but also for the rhizome of the plant Smilax glabra, which has a somewhat similar appearance when sliced thin; it is also named after fuling as tufuling.  Smilax has a reputation of being a famine food, and like fuling, it is reputed to have the medicinal effect of getting rid of excess dampness.  When material was exported under the name “China root,” the mushroom has almost always been supplied.  

Another mushroom used in Chinese medicine that grows similarly is Polyporus umbellatus (yieling the OHAI common name polyporus) which has been renamed Grifola umbellata.  It grows as a parasite mainly on oak trees (also on Liquidambar trees), and forms a relatively smaller sclerotium compared to Wolfiporia.  The grifola sclerotium is the medicinal part used in China. The Chinese name is zhuling (using the same character ling as for hoelen).   This mushroom can also send up a substantial, leafy-like, fruiting body (which hoelen rarely does).  It has been shown that zhuling does not form a sclerotium unless it is associated with a symbiotic fungus, Armillaria mellea (6, 7). Another species of Grifola, G. frondosa, for which the large flower-like fruiting body is collected, has recently been popularized as a source of immunologically-active polysaccharides, using the Japanese name maitake (Chinese: huishuhua; hua means flower).

Constituents of hoelen and Possible Effects

The primary constituent of hoelen is fiber; it is in the form of beta-glucan (chains of sugar, mostly glucose; a polysaccharide), called pachyman.  This component makes up 91–98% of the dried fungal mass, most of it being an insoluble fiber; there is virtually no lipid (less than 0.15%) and little protein (8).  To make decoctions, the mushroom mass is sliced very thin (see photo). When cooked in water to make an herbal tea, most of the insoluble fiber is left behind (though some becomes suspended by the boiling process), and virtually all the soluble fiber enters the water, forming a somewhat cloudy material.

pic3There is conflicting information about the possible immunological effect of the beta-glucan from hoelen; most of the information suggests that it is of low activity.   Some other mushrooms of the Polyporaceae, including both of the Grifola species mentioned above, contain immunologically active beta-glucans that have been developed into medicinal products by extracting and concentrating the high-molecular weight components (9).  But with hoelen, there has been little work done on isolating an active polysaccharide fraction for medicinal use.  In fact, most efforts with the material are towards developing potentially useful dietary fibers that may promote, rather than impair, mineral absorption (10).

pic4  The mushroom also contains several triterpene acids, including pachymic acid (structure image, left), tumulosic acid, eburicoic acid (a component of many mushrooms), and poricoic acid.   Some of these are actively being researched for potential medicinal uses, including anticancer effects seen in laboratory studies (used in amounts far higher than one would usually get from the crude herb).  These triterpenes may have some immunological effects as well (11), though far more research into such pharmacological activity has been done on other mushrooms, especially Ganoderma lucidum, which has a higher concentration of triterpenes (called ganoderic acids).  To study these compounds, alcoholic extracts are made, which leave behind the polysaccharides. 

Hoelen is very popular in China for making formulas that tonify the spleen and kidney, and in prescriptions that are used to remove excess dampness.  In recent years, China reportedly collected 10,000 to 13,000 tons of hoelen annually.  The main producing area was Anwei Province.

TRADITIONAL FORMULAS WITH HOELEN

While hoelen is an ingredient of many formulas, it is a major ingredient in only a few traditional formulas that are widely used today.  The following table summarizes most of these, with the % hoelen in each formula taken from Thousand Formulas and Thousand Herbs of Traditional Chinese Medicine (12):

Formula Common Name

(pinyin)

Other ingredients

% of formula

(traditional form)

Typical indications

Hoelen Five Formula

(Wuling San)

alisma, atractylodes, polyporus, cinnamon twig

19%

(powder decoction)

reduced urinary output, with edema and thirst.

Four Major Herbs Combination

(Si Junzi Tang)

atractylodes, licorice, ginseng

26%

(decoction)

spleen qi deficiency, tendency to loose stool

Cinnamon and Hoelen Formula

(Guizhi Fuling Wan)

moutan, persica, red peony, cinnamon twig

20%

(pill)

abdominal pain and masses associated with blood stasis

Vitality Combination

(Zhenwu Tang)

atractylodes, peony, fresh ginger, aconite

21%

(decoction)

fluid accumulation due to yang deficiency

Zizyphus Combination

(Suanzaoren Tang)

zizyphus, licorice, anemarrhena, cnidium

22%

(decoction)

insomnia, palpitations, sweating due to heat

Citrus and Pinellia Combination

(Erchen Tang)

pinellia, citrus, licorice, fresh ginger, mume

18%

(decoction)

phlegm accumulation with cough and loose stools

Dosage AND EFFECT

The dosage of hoelen used in decoctions as indicated in most Chinese herb texts varies from 9–15 grams for spleen/stomach disorders to 30–45 grams for edema (13).  Even higher doses have been recommended.  For example, in a treatment for schizophrenia, 60 grams of the herb was decocted for the daily dose given for 1–3 months (14).  The herb has very low toxicity.  In the traditional categorization of the herb, it is considered without taste (bland or slightly sweet) and neutral in nature (that is, relative to warming or cooling properties).  In the formulas listed in the table above where the decoction form is used, 9 grams was indicated in each case for the quantity of hoelen, the lowest dose recommended in the Materia Medica.  Generally, reports from modern Chinese clinical work indicate use of somewhat larger amounts than that (typically 10–30 grams for a one day dose).  By contrast, hoelen is sometimes incorporated into pills, either as a powder or extract, and its daily dosage in that case is quite low. 

The glucans may have a soothing effect on the stomach and intestines, which can explain the role of hoelen in formulas that treat nausea, vomiting, diarrhea, loss of appetite, stomachache, and stomach ulcer, as well as cases of excess phlegm production that may result from stomach irritation (15).  This effect will be stronger in decoctions than with the pills because of the higher dosage involved, but even the lower dosages may have an effect due to direct contact of the herb constitutents with the stomach and upper portion of the intestines. 

The triterpenes may be responsible for other claimed effects, such as diuretic activity; hoelen is often combined with alisma (zexie), which also has triterpenes and is considered a diuretic (16).  In addition, these compounds can also have a benefit for the digestive system.  The amount of the triterpenes in hoelen is small, so in order to get an effect of them outside of the stomach and upper intestine, it is important to use decoctions or dried decoctions (e.g.  for treating edema and insomnia).

The attribution of a sedative effect to hoelen (and especially to fu-shen, which is now defined as the smaller hoelen fungus with the pine root embedded in it) seems largely the result of the imagination of the ancient alchemists (17) and there is currently little supporting evidence for it.  Hoelen was originally thought to arise as the result of transformation of pine resin.  It was said that after a thousand years residing in the ground, the resin became hoelen; after another thousand years, it became fushen; after another thousand years, it become amber (hopu, which is, in fact, derived from pine resin); and after yet another thousand years, it became crystal quartz (the term “thousand years” means a long time, and not the specific duration).   The pine tree is itself a symbol of calmness, and the four “derivatives of pine resin” described here are all considered sedatives of increasing potency to accompany the aging in the ground under the influences of earthly and heavenly qi.   While this story in interesting, it raises the question whether the fungus truly has significant sedative properties, since its constituents are entirely different from pine roots, amber, and quartz.

References

 

 

 June 2006